1. Field of Invention
The present invention relates generally to the field of hand splints. More specifically, the present invention is related to flexible modular hand splints for use in treating hand dysfunction associated with central and/or peripheral nervous system injury.
2. Discussion of Prior Art
Experts in the management and treatment of hand dysfunction will recognize the therapeutic value of the Modular Upper Extremity Support System (MUESS) in treating hand dysfunction in children and adults with, but not limited to, the following diagnoses: cerebral palsy, cerebral vascular accident (stroke), traumatic brain injury, spinal cord injury, hydrocephalus, benign congenital hypotonia, dystonia, brachial plexus injury, and carpal tunnel syndrome; all of which involve an insult to the central, and/or peripheral nervous systems. However, for illustrative purposes, the present invention will be discussed in reference to hand dysfunction in children with cerebral palsy, a condition involving disruption of the complex organization and integration of the sensory and motor structures and pathways of both the central and peripheral nervous systems.
Children diagnosed with cerebral palsy (CP) experience decreased, increased, and/or fluctuating muscle tone which results in an imbalance of directional forces that manifest as stereotypical postures and movement patterns. For example, children with CP characteristically display hand and/or arm posturing with a reduced range of active motion which is typified by wrist and finger flexion, thumb adduction, ulnar deviation, and hand, wrist, and forearm pronation. These postures and movement patterns can result in contractures which further restrict movement and lead to mild to severe hand dysfunction.
The probability of improving hand function depends in part on the underlying cause and severity of the impairment, the services received, and the cognitive and visual status of the individual. However, even small improvements in hand function can be motivational and empowering, and contribute to increased independence in performing activities of daily living.
The development of hand skills follows a fairly predictable progression from infancy, through childhood and into the teen-age years. Those with expertise in the sensory-motor development of children are familiar with this pattern, and understand that neurological insults, whether experienced prenatally, neonatally or postnatally, may result in mild to severe disruption of this developmental pattern, ultimately leading to varying degrees of dysfunction and/or deformity. However, it is now widely accepted in the field of sensory-motor development that the plasticity of the nervous system offers the potential for improvement in sensory and motor function throughout life when appropriate therapy is implemented.
In the earliest stage of sensory-motor development, infants react automatically and reflexively by moving their arms and hands in response to tactile and proprioceptive somatosensory stimulation. As the nervous system matures, infants typically gain more control over reflexive responses, generally by six months of age. From that point forward, ongoing neurological maturation and environmental cues further promote hand skill development which progresses from voluntary motor patterns of grasp, release, and bi-manual skills in young children to refinement of fine motor skills during teen-age years and into adulthood.
However, infants and young children with cerebral palsy often have low proximal and distal muscle tone initially, followed later by high distal tone, the latter which often becomes apparent when they experience physical or emotional distress as might be experienced when attempting to move against gravity. Unable to counter the pull of gravity due to low proximal muscle tone, these children may try to stabilize with their extremities when making the effort to move away from a supporting surface, which in turn leads to high distal tone making it very difficult for them to hold their own weight and remain upright against gravity. The stress of the circumstance increases muscle tone in the extremities as the child pulls down to the supporting surface, making an attempt to stabilize in synergistic patterns of flexion and/or extension, often manifested with stereotypical posturing of the upper extremities into shoulder internal rotation, elbow extension, finger and wrist flexion, ulnar deviation, and pronation, further leading, over time, to contractures of the soft tissues.
Subsequently, the learned motor patterns of young children with neurological deficits may be dominated by reflexive behaviors which lack voluntary control and lead to dysfunctional grasping patterns that resemble those of infants of six months of age or younger, leaving them with severely restricted range of motion.
Individuals with neurologic injuries may have deficits in fine motor skills that range from mild impairments of hand function to more severe patterns that require orthotic support of the hand, wrist, and forearm. Often orthotics are designed to improve bone and joint alignment to prevent the development of contractures (tightening of soft tissues). Such orthotics, however, tend to be immobilizing which can further hinder the development of functional hand use.
Prior art modular wrist splint systems such as those described in U.S. Pat. Nos. 4,369,775 and 7,537,577, as well as US Patent Application Publication 2011/0054371 are overly restrictive and do not allow the flexibility in hand movements allowed by the MUESS while still providing the support needed for changing, functional requirements.
Whatever the precise merits, features, and advantages of the above cited references, none of them achieves or fulfills the purposes of the present invention.
The MUESS supports and positions the hand, wrist, and forearm to optimize and facilitate both passive and active movement resulting in improved hand function. In children with cerebral palsy, the imbalance of directional forces is most evident clinically at the wrist and thumb, which typically manifests as a synergistic pattern of wrist and finger flexion, thumb adduction, ulnar deviation, and forearm and hand pronation. Thus the focus of the invention is to first establish improved balance of flexion and extension at the wrist, along with thumb abduction which optimally positions the hand, wrist, and forearm for functional movement originating at the joints of the wrist and thumb. By increasing stability through improved alignment of the bones, the MUESS promotes functional mobility through the joints of the hand, wrist, and forearm. When integrated into other early intervention services, the MUESS system improves hand function in children with neurological injuries. The MUESS also increases tactile and proprioceptive somatosensory input through gentle compression of the hand, wrist, and forearm, which benefits individuals with nervous system deficits who may have significantly reduced opportunities to receive, experience, interpret and integrate sensory-motor information.
It is proposed that the present invention addresses, and reasonably meets, the aforementioned needs. The components of the Modular Upper Extremity Support System (MUESS) interact dynamically to provide combinations of stability and mobility which increase the potential for improved functional hand use and skill acquisition in individuals with central and/or peripheral nervous system disorders having mild to severe impairments in hand function.